Initial Inspection and Diagnostic Overview
TroubleshootingSpecial Tool Required:
MPCS Service Connector 07WAZ-001010A
1. Check the driver's No. 9 and the passenger's No. 13 fuses.
Are the fuses OK?
YES - Go to step 2.
NO - Find and repair the cause of the blown fuse.
2. Turn the ignition switch ON (II). If the driver's seat belt is unbuckled, the seat belt reminder will beep five times.
3. Check self-diagnosis function Mode 1 for a diagnostic trouble code (DTC) by connecting the special tool to the multiplex control inspection socket (A). After about 5 seconds, the ignition key light should come on and the beeper should beep for 2 seconds, go off for 0.2 second, then blink and beep for 0.2 second. This means that you are in Mode 1 of the self-diagnosis function.
4. If there is a DTC, it will blink/beep, pause, then repeat the DTC as long as the ignition switch is ON (II).
Is there a repeating DTC?
YES - Count the blinks/beeps, then go to step 7.
NO - See if the SCS circuit is working properly. Go to step 5.
5. Check for continuity between the No. 3 terminal in the inspection connector and the A15 terminal in the driver's unit.
Is there continuity?
YES - Go to step 7.
NO - Repair the open in the wire, and recheck for DTCs.
6. Check for continuity between the No. 1 terminal of the inspection connector and body ground.
Is there continuity?
YES - Go to step 12.
NO - Replace the driver's under dash fuse/relay box and recheck for DTCs.
7. One second after you go into self-diagnosis mode 1, the ignition key light and beeper indicate the DTC, and repeat it every 3 seconds. If there is more than one DTC, the system will indicate them in ascending order, beginning from the DTC with the lowest numerical value. Find your DTC in this table, then go to step 8 and check the communication lines.
8. With the ignition switch OFF, check for continuity according to the table.
Is there continuity?
YES - Go to step 9.
NO - Check for an open in the wire.
9. Turn the ignition switch ON (II), and check for voltage between the communication line and ground.
Does the voltage match the table?
YES - Communication lines are OK. Go to step 10.
NO - Repair the line according to the following.
- If the voltage is too high:
- Check for a short to another wire.
- Check for poor contact in the connector at the receiving unit.
- If the voltage is too low:
- Check for a short to ground or to another wire.
- Check for poor contact at the connector on the transmitting unit.
- Faulty circuit in the transmitting unit.
10. Shift to the sleep mode:
- Turn the ignition switch OFF.
- Cancel the key-off operation timer in the power window system by opening and closing one of the doors.
- Make sure that the exterior lights are off. If you do not operate any switches related to the multiplex control units within one minute after meeting the above conditions, the system function shifts to the sleep mode. (All of the switches must be turned OFF except door lock knob switches).
11. Confirm the sleep mode:
- Check for voltage between each communication line and body ground while shifting to the sleep mode. There should be battery voltage.
- Check the parasitic draw at the battery while shifting to the sleep mode. Amperage should change from about 70 through 80 mA to less than 10 to 20 mA.
12. Confirm the wake up mode.
- When the ignition switch is turned ON (II), all of the multiplex control units wake up at the same time without "talking" to each other through the communication lines.
- When any switch in the multiplex system is turned on, it wakes up its related control unit which, in turn, wakes up the other units.
After confirming the sleep mode, look in the following tables for the switch most closely related to the problem. Operate that switch and see if its control unit wakes up.
NOTE: If any control unit is faulty and will not wake up, several parts of the system will malfunction at the same time.
In each table, the control unit is followed by a list of the switches and input signals that can wake it up.
Is the wake-up function OK?
YES - Troubleshoot the individual system function that had a problem. Go to step 13.
NO - Test power and ground to all three multiplex control unit .
13. From Mode 1, disconnect the special tool from the multiplex control inspection connector for about 10 seconds, then reconnect it. The ignition key light should come on and the beeper should beep for 2 seconds, then blink and beep twice more at 0.2 second intervals. This means the system has gone from Mode 1 to Mode 2.
NOTE: To cancel mode 2, disconnect the SCS service connector from the multiplex control inspection connector for more than 10 seconds or turn the ignition switch OFF.
14. Look in the following tables for the switch most closely related to the problem. While still in Mode 2, operate the switches to test the circuits between the switches and their control units. If the circuit is OK, the ignition key light should blink once and the beeper should beep once. If the circuit is faulty, there will be no indication.
Does the ignition key light blink and beeper beep?
YES - The circuit is OK. Refer to the test(s) for that individual system.
NO - Go to step 15.
In each table, the control unit is followed by a list of circuits that it can check in Mode 2.
The key cylinder switches should only beep/flash when turned to LOCK or UNLOCK. If they beep/flash when returning to the neutral position, the switch is defective or misaligned. Adjust or replace the affected key cylinder switch.
15. Check 2 or 3 more circuits listed for that control unit.
Does the ignition key light blink and the beeper beep for each circuit?
YES - The additional circuits are OK. Repair the short or open in the circuit that failed the test in the preceding step.
NO - Multiplex failed circuits can mean that the control unit has failed without triggering a DTC. Test a few more circuits. If they also fail, substitute a known-good control unit, then recheck. If the system works properly, the original control unit is faulty, replace it. there is still a malfunction, substitute a know-good control unit for the next most likely faulty control unit, then recheck. If the system works properly, that control unit is faulty; replace it.